Answer:
He developed the concept of concentric electron energy levels
Explanation:
Before Bohr's model, Rutherford's model was proposed. This model explains most of the properties of the atom but failed to explain the stability of the atom.
As per Rutherford's model, electrons revolve around the nucleus in the orbit.
But revolving electron in their orbit around nucleus would give up energy and so gradually move towards the nucleus and therefore, eventually collapse.
Bohr's proposed that the electrons around the nucleus move orbit of fixed energy called "stationary states". Electrons in these stationary states do not radiate energy.
Therefore, proposal of concentric electron energy levels refine the atomic models.
Removing seed casings from grains is SEPARATING. a soda bubble bubbling when it is opened is MIXING. a bright copper statue turning green is MIXING. remove salt from seawater is SEPARATING. water decomposing is SEPARATING.
<span>Minerals are solid substances that occur naturally. They can be made from a single element (like gold or copper) or from a combination of elements.</span>
Answer: so the answer is A
Explanation: The relationship between an object's mass (m), its acceleration (a), and the applied force (f) is F=ma. ... This law requires that the direction of the acceleration vector is in the same direction as the force vectors.
